1. Field of the Invention
The present invention relates to a presence service system, a presence apparatus, a presence service method, and a presence service program in which for a presence service, a presence notification policy is set according to change in a state.
2. Description of the Related Art
The presence service is a service to exchange presence information items indicating states, i.e., presence of human beings, articles or items, and services. IETF RFC2778 http://www.ietf.org/rfc/rfc2778.txt describes a basic architecture of the presence service. Clients using the presence service are classified into two types of clients, i.e., presentities (on an information delivery side) such as users providing presence information and watchers (on an information receiver side) observing the presence information. The presence service is a service in which the presence information is received from presentities and is then delivered to watchers.
In an operation in which a user provides presence information from an information processing terminal (to be referred to as a presence client terminal hereinbelow), to protect privacy of the user, it is required to conduct processing to reject a subscription request from a watcher, processing to partly conceal the contents of presence information to be sent to a watcher, or processing to convert the presence information into obscure information by the presence client terminal or a server device (to be referred to as a presence service server hereinbelow) communicating with the presence client terminals. The access control processing is carried out according to a predetermined policy called a presence notification policy. It is required for the user to set the presence notification policy in advance.
The commonly known methods of setting a presence notification policy in the prior art include a method in which a correspondence is established between an identifier of a watcher and a presence notification policy. There also exists a method employing a group in which an identifier of each watcher is registered in advance and the group is related to a presence notification policy. However, these methods are attended with problems. That is, since a presence notification policy is set to an identifier of a watcher or a domain to which a watcher belongs, it is necessary to obtain the identifier or the domain of the watcher to set the presence notification policy to the watcher or the domain. Another problem also appears in association with a new watcher. Each time a new watcher is designated, the watcher is related to a presence notification policy or a group of the watcher is registered for the assignment of the presence notification policy. This leads to a disadvantage that much load is imposed onto the user.
Additionally, Japanese Patent Application Laid-Open Ser. No. 2005-10874 describes a conventional technique for the presence service. According to the technique, “presence control apparatus” is devised for information delivery on assumption that the information provider can designate a user as an information delivery destination with conditions and the user also can specify conditions for information and an information provider where the conditions change frequently.
However, Japanese Patent Application Laid-Open Ser. No. 2005-10874 describes only the registration of conditions regarding information delivery. It is not possible in accordance with the invention to conduct operation in which a condition and a method of notifying presence information are registered as a pair such that a notification method is changed based on which condition is satisfied. Since the information delivery side and the information receiver side mutually specify a condition, privacy of the information delivery side cannot be sufficiently protected.